Posted by Everett J. Prescott on Feb 19, 2016 10:58 AM

*Updated April 9th, 2020*

When you tie into an existing water main, you can either shut down the whole system to insert the tap or wet tap it while the system is still under pressure. Many municipalities are not familiar with how wet tapping works, so they use the same old technique they always have: shutting down the whole system. Unfortunately, that technique creates a lot of extra work, with pipe dewatering requiring that the water be tested for bacteria once it's turned on again according to regulations under the Safe Drinking Water Act. It also requires that a boil order be activated for all customers receiving water through that service. With wet tapping, you simply go on with your day. Let's look at what wet tapping is, how it works and the benefits and drawbacks of this technique.

worker-wet-tapping-pipelineWhen you do wet tapping, you place a tapping fitting on the water main in addition to a valve to control the water at that line. Once the fitting and valve are in place, the main is tapped. Once the drill is pulled back, the valve is closed, keeping water from leaking out of the main. It's a pretty simple process that helps you avoid additional testing and boil orders that are required when a water main is dewatered. At the same time, your customers are still receiving water and you can undertake the operation during regular business hours. Here's how it works:

  • The tapping fitting is put in place on the water main and secured solidly.
  • A gate or ball valve is installed and left wide open.
  • Opposite of the main on the valve, a tapping machine is attached, with a cutting head and watertight housing.
  • The tapping machine is started and the cutting head advanced to cut through the main.
  • The tapping machine, valve and fitting are all securely fitted, preventing loss of water pressure.
  • Once the cut is done, the cutting head is withdrawn into the tapping machine and the valve is closed.
  • The tapping machine is removed from the valve, leaving a functional valve and tap in place with no loss of service.

two-men-working-on-live-pipeline-tappingUsing a wet tapping system helps you avoid the problem of unhappy customers because their service and pressure are not impacted by the addition of a new tap. The wires on the cutting head retain the piece of the main that's been removed, so you don't get debris in the system. In rare circumstances when working on older, corroded pipes that don't hold up well to attaching the tap fitting, referred to as burn through, but most pipes corroded that badly won't work with any additional fittings and should be replaced. Wet tap fittings can be more costly than regular fittings, but are more cost-effective in the long run. Hot tapping is also an option for many other pipeline tapping needs, including several gasses and fluids used in both municipal and industrial complexes, providing additional usage for a tapping machine.

Now that you have a better understanding of wet tapping, why not take the time to consider incorporating it into your options when it's time to add a new service line? At Team EJP, we're happy to help with any questions you have about new products or techniques. Please feel free to contact us today for more information on wet tapping for waterworks companies and organizations.

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